[GRASS-user] Datum not recognized by Grass

[Zoltan Szecsei]

Hi Helmut,
Thanks for your comments.

I installed everything with OSGeo4W64, and QGIS get the EPSG:2932 but 
Grass not.

Perhaps I have a PATH or some other setting problem?
Perhaps let me know what search paths Grass uses for proj4, and what 
proj files and locations I should scan for.

Regards,
Zoltan

On 2019/12/04 01:30, Helmut Kudrnovsky wrote:
>> ignore the warning and use GRASS with PROJ6, granted that authority name
> (e.g. EPSG) and authority code (e.g. 2932) are known for both CRS's in case
> of reprojection
>
> this issue is already by GRASS with PROJ6, see
>
> ####################
> GRASS version: 7.8.1
> Code revision: c865432c9
> Build date: 2019-11-10
> Build platform: x86_64-w64-mingw32
> GDAL: 3.0.2
> PROJ: 6.2.1  <=
> GEOS: 3.8.0
> SQLite: 3.29.0
> Python: 3.7.0
> wxPython: 4.0.7
> Platform: Windows-10-10.0.18362-SP0 (OSGeo4W)
> ####################
>
> and the output from the underlying PROJ: 6.2.1
>
> ####################
> C:\>projinfo EPSG:2932 -o PROJ,WKT2_2018
> PROJ.4 string:
> +proj=tmerc +lat_0=24.45 +lon_0=51.2166666666667 +k=0.99999 +x_0=200000
> +y_0=300000 +ellps=intl
> +towgs84=-119.4248,-303.65872,-11.00061,1.164298,0.174458,1.096259,3.657065
> +units=m +no_defs +type=crs
>
> WKT2_2018 string:
> PROJCRS["QND95 / Qatar National Grid",
>      BASEGEOGCRS["QND95",
>          DATUM["Qatar National Datum 1995",
>              ELLIPSOID["International 1924",6378388,297,
>                  LENGTHUNIT["metre",1]]],
>          PRIMEM["Greenwich",0,
>              ANGLEUNIT["degree",0.0174532925199433]],
>          ID["EPSG",4614]],
>      CONVERSION["Qatar National Grid",
>          METHOD["Transverse Mercator",
>              ID["EPSG",9807]],
>          PARAMETER["Latitude of natural origin",24.45,
>              ANGLEUNIT["degree",0.0174532925199433],
>              ID["EPSG",8801]],
>          PARAMETER["Longitude of natural origin",51.2166666666667,
>              ANGLEUNIT["degree",0.0174532925199433],
>              ID["EPSG",8802]],
>          PARAMETER["Scale factor at natural origin",0.99999,
>              SCALEUNIT["unity",1],
>              ID["EPSG",8805]],
>          PARAMETER["False easting",200000,
>              LENGTHUNIT["metre",1],
>              ID["EPSG",8806]],
>          PARAMETER["False northing",300000,
>              LENGTHUNIT["metre",1],
>              ID["EPSG",8807]]],
>      CS[Cartesian,2],
>          AXIS["(E)",east,
>              ORDER[1],
>              LENGTHUNIT["metre",1]],
>          AXIS["(N)",north,
>              ORDER[2],
>              LENGTHUNIT["metre",1]],
>      USAGE[
>          SCOPE["unknown"],
>          AREA["Qatar - onshore"],
>          BBOX[24.55,50.69,26.2,51.68]],
>      ID["EPSG",2932]]
> ####################
>
>> The problem is that GRASS still assumes datum transformation from X to
> WGS84, whereas with PROJ6,
>> WGS84 is no longer required as pivot datum. Datum transformations from
> datum X to datum Y can
>> sometimes (often) be done without going through WGS84. The requirement is
> to have EPSG or other
>> authority codes and to use PROJ 6.
> this warning is just from a simple v.in.ogr of a EPSG:2932-based shapefile
> into a EPSG:2932-created GRASS location.
>
> so, there may be some more adaptions needed for actions like v.in.ogr and
> co?
>
>
>
> -----
> best regards
> Helmut
> --
> Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html
> _______________________________________________
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-- 

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Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

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